Dipartimento di Fisica - Tesi di Dottorato

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Questa collezione raccoglie le Tesi di Dottorato afferenti al Dipartimento di Fisica dell'Università della Calabria.

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<> modelling study of atmospheric cycle of mercury and its exchange processes at environmental interfaces
(2015-12-18) De Simone, Francesco; Bertolini, Roberto; Carbone, Vincenzo; Pirrone, Nicola; HedgecocK, Ian M.
Since ancient times human activities have significantly altered the natural global Mercury (Hg) cycle through emissions to the environment. Hg is a global pollutant since its predominant atmospheric form, elemental Hg, reacts relatively slowly with the more abundant atmospheric oxidants and is therefore transported long distances from its emission source. Once oxidised however Hg is readily deposited, an can then be converted to the toxic monomethylmercury (MeHg) in soils and natural waters. MeHg is able to bioaccumulate and biomagnify, up to levels at which it is harmful to human health. Mercury pollution is therefore a threat to ecosystem health on a global scale, and is now being addressed by an international agreement, the Minamata Convention. Comprehensive knowledge of the details of the atmospheric Hg cycle is still lacking, and in particular there is some uncertainty regarding the atmospherically relevant reduction-oxidation reactions of mercury and its compounds. The exchange of Hg and its compounds between the atmosphere and the oceans also plays an important role in the cycling of mercury in the environment: understanding and quantifying mercury deposition patterns and fluxes is critically important for the assessment of the present, and future, environmental impact of mercury contamination. ECHMERIT is a global on-line chemical transport model, based on the ECHAM5 global circulation model, with a highly customisable chemistry mechanism designed to facilitate the investigation of both aqueous and gas phase atmospheric mercury chemistry. An improved version of the model which includes a new set of emissions routines, both on-line and off-line, has been developed and used for this thesis to investigate and assess a number of the uncertainties related to the Hg atmospheric cycle. Outputs of multi-year model simulations have been used to validate the model and to estimate emissions from oceans. Various redox mechanisms have been included to assess how chemical reactions influence the models ability to reproduce measured Hg concentrations and deposition flux patterns. To characterize the Hg emissions which result from Biomass Burning , three recent biomass burning inventories (FINNv1.0, GFEDv3.1 and GFASv1.0) were included in the model and used to investigate the annual variation of Hg. The differences in the geographical distribution and magnitude of the resulting Hg deposition fluxes, hence the uncertainty associated with this Hg source, were quantified. The roles of the Hg/CO enhancement ratio, the emission plume injection height, the Hg0 (g) oxidation mechanism and lifetime, and the inventory chosen, as well as their uncertainty were considered. The greatest uncertainties in the total deposition of Hg due to fires were found to be associated with the Hg/CO enhancement ratio and the emission inventory employed. Deposition flux distributions proved to be more sensitive to the emission inventory and the oxidation mechanism chosen, than all the other model parameters. Over 75% of Hg emitted from biomass burning is deposited to the world’s oceans, with the highest fluxes predicted in the North Atlantic and the highest total deposition in the North Pacific. The net effect of biomass burning is to liberate Hg from lower latitudes and disperse it towards higher latitudes where it is eventually deposited. Finally, the model was used to evaluate the fate of the Hg released into the atmosphere by human activities. Anthropogenic emissions are estimated to amount to roughly 2000Mg/y (1000-4000 Mg/y). Hg speciation (elemental, oxidised or associated with particulate matter) is subject to many uncertainties: the extremely variable lifetimes among Hg species, as well as the Hg emission heights, in combination with the complex physical and chemical mechanisms that drive its final fall-out lead to considerable uncertainties. To address this specific issue three anthropogenic Hg emission inventories, namely AMAP-UNEP, EDGAR and Streets, were included in the Model. Different model parametrisations were adopted to trace the fate of Hg to its final receptors and to thoroughly test the model performance against the measurements. Primary anthropogenic Hg contributes up to 40% of the present day Hg deposition. The oxidation mechanism has a significant impact on the geographical distribution of the deposition of Hg emitted from human activities globally, : 63% is deposited to the world’s oceans. The results presented in this thesis provide a new and unique picture of the global cycle of mercury, evaluating and assessing the uncertainties related to many aspects with an on-line Global Circulation Model developed specifically to investigate the global atmospheric Hg cycle.
<> proposal of efficient routing techniques and intelligent vehicular traffic management in the smart cities context, through distributed wireless networks
(2016-02-02) Sottile, Cesare; Pantano, Pietro Salvatore; De Rango, Floriano; Marano, Salvatore
In this thesis, the design of e cient techniques for routing protocol suitable to Vehicular Ad-hoc NETworks (VANETs) has been pro- posed. In particular, the aims of the proposed protocols are to reduce interference issues, due to the data transmissions in wireless environ- ment. The proposed protocols use time series prediction models and also multi-objective metric, based on the evaluation of co-channel in- terference levels, end-to-end delay, and link duration probability along the di erent links from sources towards destinations. These param- eters are modelled through an optimization problem. The key fac- tors are to exploit the advantages available to the Standard 802.11p, based on a dynamic allocation mechanism of the DSRC spectrum, aimed at the reduction of the co-channel interference and the maxi- mization of the link duration probability (two key issues in vehicular environments). Another topic discussed in this thesis is related to the smart vehicular tra c management through VANETs infrastructure and communications(V2I and V2V). A distributed algorithm with the aim to build less congested path for the vehicles in a urban scenario has been developed. It is also considered the problem regarding to enhance air quality around the cities reducing the vehicles CO2 emis- sions. There are di erent causes related to the CO2 emissions such as the average travelled time spent by vehicles inside the city and their average speed. Hence, with a better tra c management the average time spent by the vehicles in the city will be considerably reduced as well as CO2 emissions. These results are demonstrated in a discrete event simulator by using also real tra c data
<> study wind behavior from the micro to the mesoscale of different temporal and spatial horizons: turbulent regime, mean and climate
(2014-11-13) Tiriolo, Luca; Bartolino, Roberto; Sempreviva, Anna Maria; Carbone, Vincenzo
Absorpitive losses mitigation in gain-plasmon hybrid systems as optical metamaterials
(2013-11-29) Rashed, Alireza Rahimi; Bartolino, Roberto; Versace, Carlo C.; Strangi, Giuseppe
In the past decade, plasmonic nanoparticles (NPs) have gained a lot of interest due to their exceptional and fascinating properties which have been accomplishing vital role in emerging science and technology towards multifunctional applications. The extensive current research efforts in nanoplasmonics trigger towards various opto-electronic and medical applications such as invisibility, perfect lens, increasing the efficiency of solar cells, designing and extra-sensitive single-particle detection of biomolecular recognition and in particular optical metamaterials. The negative real part and the low value of the imaginary part of dielectric permittivity are crucial for applications of nanoparticles as subunits of optical metamaterials. However, the performance of plasmonic nanostructures is significantly limited by the intrinsic and strong energy dissipation in metals, especially in the visible range. In fact, regardless of the challenges to synthesize plasmonic nanostructures, the path to use them as building blocks of optical metamaterial is crossing through the finding a solution to mitigate their optical losses. In this research thesis, it is demonstrated experimentally that the incorporation of gain material such as organic dye molecules and quantum dots in close proximity of enhanced local fields of various properly designed plasmonic systems makes it possible to induce resonant energy transfer processes from gain units to plasmonic nanoparticles, to accompanish loss compensation in optical metamaterials. Steady-state experiments and time resolved spectroscopy along with modification of Rayleigh scattering and optical transmission of a probe beam as a function of impinging energy are crucial evidences of mitigation of absorptive losses in different gain doped plasmonic systems The strategy that has been followed here towards mitigation of absorptive losses in optical metamaterials acts at different spatial scales from nano to macro (see Figure 1). The systems at nano-scale (10-100 nm) are based on dispersion of NPs, in particular, gain assisted (nanoparticle-dye dispersion), gain-functionalized core-shell gold NPs (encapsulated dye molecules into the shell) and dye grafted gold core multimeric nanostructures. The study of such nano-composites allows to recognize experimentally how the parameters such as the geometry and size of the metal nanostructures, inter-particle distance, overlap between emission spectrum of gain material and plasmon band of metal NPs, concentration and quantum yield of donor molecules are playing an important role to create more efficient nonradiative RET processes from donor molecules to acceptors. Figure 1 The followed spatial stages on this research study ranged from (a) nano-scale and (b) mesco scale towards (c) macro scale. The obtained results in nano-scale generate further motivations to move forward to study meso-scale (100-900 nm) plasmonic systems which include both dispersion (nanoshell composites) and bulk (periodic layers of gain materials and lossy metal elements) systems. The nanoshells which are consisted of dye doped dielectric core coated gold shell dispersed in ethanol solution are designed with an optimized ratio of core diameter and metallic shell thickness. The time resolved fluorescence spectroscopy results along with pump-probe experiments on nanoshells are convincing evidences for optical loss mitigation. Finally in third stage, the optical properties of gain-plasmon composites dispersed in PDMS host matrix as an example for bulk samples at the macroscopic scale (1 μm and beyond) have been investigated. The achieved results on this stage can help to design and fabricate such plasmonic structures that lead from fundamental physics towards practical applications. In this regard, the first four chapters provide the background concerning the main elements of this research work. The first chapter contains an introduction to the metamaterials. Second chapter describes the optical properties of plasmonic nanostructures. In third chapter, gain materials and the optical processes beyond these materials have been investigated. The fourth chapter deals with the optical properties of hybrid systems consisted of active materials and nano-plasmonic elements. After providing a brief introduction regarding the applied setups and instruments in this research study in chapter five, the last three chapters represent the acquired experimental results in each mentioned spatial scale. In chapter six, the optical properties of nano-scaled gain-plasmon systems in solution including gain-assisted, gainfunctionalized and dye grafted multimeric samples are investigated. Chapter seven explores the optical characteristics of dispersion of nanoshell sample as an example of the study in mesoscale. Finally, the thesis is completed with the study of the optical features of macro-scaled bulk samples based on core–shell type quantum dots and gold NPs dispersed in PDMS, and a short conclusion of this research study. This study emphasizes effective progress in materials science and paves the way towards further promising scientific research aimed to enable the wide range of electromagnetic properties of plasmonic metamaterials
Across Scales Approach Based on Exciton-Plasmon Coupling for Low Loss Optical Metamaterials
(2015-12-15) Dhama, Rakesh; Bartolino, Roberto; Versace, Carlo; De Luca, Antonio
Active plasmonic nanostructures for biomedical applications
(Università della Calabria, 2020-03-27) Chatterjee, Sharmistha; Bartolino, Roberto; Strangi, Giuseppe
Real-time and label-free detection of protein molecules at ultralow concentration in their natural state is considered the “Holy-Grail” in biomedical research. Protein molecules pop up in the bodily fluids such as saliva, blood serum, at early stage of any infection or disease and circulate throughout the body. Therefore, the emergence of that particular infection or disease can be envisioned through the detection of the signature protein markers. The early detection of the disease would help to start the treatment early, and thus ensure therapeutic success which will eventually increase the survival rates and quality of life. The early detection of protein molecules is necessary for the diagnostics as well as for environmental monitoring, emergency response and homeland security. But the desired detection of protein molecules in the early stage is extremely challenging because of the ultralow concentration of the protein markers in the bodily fluid at the early stage and their acutely small size (< 3 nm). One way to overcome this hurdle is to use the extraordinary electromagnetic responses of noble metal nanoparticles (MNPs). Here stable gold nanostars (AuNS) have been synthesized to use their property for sensing. A surfactant-free, simple, one step wet-chemistry method was used to synthesize these spiky nanoparticles, which were stable in aqueous media for more than five months. Based on their characterization and the numerical analysis, it has been realized that these nanoantennas could be an efficient agent for the early detection of disease. Furthermore, for the marker detection, the heterodimeric nanogap, created between a nanostar antenna tip and a gold nanosphere, was seen to be more effective than those single nanostar antennas because of their higher intensity enhancement capability and also the optimum electric field map at the hot-spots which acts as the binding site for molecule. Both the AuNS antenna and the hybrid one could be easily converted to a biosensor, by anchoring suitable anti-bodies on the surface of the nanoantenna. Surprisingly, these gold nanostar antennas were seen to have both the non-edge breathing modes and the well-known edge dipolar mode. The optically active edge dipolar mode will be useful for the detection of protein molecules by using their localized surface plasmon resonance (LSPR) effect which is same as any conventional plasmonic biosensor. But the non-edge breathing modes of nanostar antenna will be helpful to determine the mass of adsorbed analyte based on the cantilever principle. The mass estimation (having the information about the polarizability and the size) of the markers is very crucial because it would provide the information about the number of amino acids present in that molecule which will help for better understanding of its molecular structure and thus will be useful for designing its anti-agent. This efficient acousto-plasmonic nanoantenna therefore could become a key element at a point of care. To go one step forward in this research area, Fano-lineshape based sensing was thought to be a promising idea. Here the reported Fano line-shape arises from the coupling of the gold nanorods dipped in thermo-responsive polymer matrix and a silver thin film. The Fano system was seen to respond to both the change in external temperature and the refractive index. This kind of Fano system will be helpful for the label-free detection of the foreign protein molecule with high efficiency and also for identifying the marker’s thermodynamic state and reactions of the molecule which is crucial for protein engineering. All these constitute the base of the discussion of part I of the thesis which is about the light harvesting plasmonic nanoantennas. In the 2nd part of the thesis, AZO metasurfaces and their optical activities are discussed. Aluminium doped Zinc Oxide (AZO) is a low-loss material and popular as an alternate plasmonic material. The highly ordered AZO nanotubes array system has seen to have gas sensing capability. The reported H2 gas detection within a very short time can make this system suitable for industrial application. The detection of H2 gas of lower concentration with the help of these nanostructures is also useful to detect the presence of bacteria by tasting their exhaled H2 gas. On the other hand, the AZO solid nanopillars arrays are seen to have generalized Brewster angle phenomena which can be useful for many applications including the optical switching. Lastly, some additional works have been described in a brief way. In this section, photonic nanojet related theoretical study, asymmetric sound transmission behaviour shown in 3D printed acoustics metamaterials, focal-length tunability of metalens and plasmon assisted cancer therapy has been reported. As per my belief and understanding, all these studies reported in this thesis will enrich the related research areas.
Active plasmonics in soft matter doped with gold nanoparticles plasmonica attiva in materia soffice drogata con nanoparticelle d'oro
(2013-11-29) Cataldi, Ugo; Bartolino, Roberto; Caputo, Roberto; Versace, Carlo C.
The main objective of this study is active plasmonics. The work has been focussed on the design, characterization and theoretical interpretation of novel systems. Top-down and bottom-up, self-assembling, approaches have been utilized to realize devices where spherical gold nanoparticles have been periodically and randomly arranged. Two main paths have been followed to achieve this goal. In the first one, by utilizing a rigid periodic structure as a host platform for soft-matter (cholesteric liquid crystals) mixed with plasmonic nano-entities, was possible to obtain a chirally-organized tuneable plasmonic system. The tunability of the obtained device has been induced by applying temperature changes or external electric fields. In the second one, the surface of an elastomeric platform has been randomly covered by gold-nanoparticles. Controlled nano-chemistry processes have been successively applied to the nanoparticles (immobilized on the surface) to locally increase their size. The elastic properties of the template together with the increased size of particles have allowed a systematic study of the coupling between near-fields of the spherical nanostructures. Colloidal nano-chemistry technics have been utilized both to synthetize spherical gold nano-particles and to increase their sizes. Spectroscopic analysis has been used to analyse the response of obtained structures under electrical, thermodynamical and mechanical stimuli. SEM and TEM imaging have been exploited to study the morphology of devices, the shape of nano-structures and to measure their sizes. Moreover, from SEM images, through the use of a MatLab code written to the purpose, it has been possible to extract fundamental parameters used to perform a theoretical analysis of experimental results
Adsorption properties of carbon nanotubes and application of thermal desoprtion spectroscopy to ammonia and methane ices and zoisite
(2010-12-14) Vasta, Roberta; Bonanno, Assunta; Falcone, Giovanni
In this work we wanted to underline the importance of Thermal Desorption Spectroscopy and its applications to several branches of Physics. Temperature-programmed desorption techniques (TPD) are important to determinate kinetic and thermodynamic parameters of desorption processes and decomposition reactions. Knowledge of the nature of the desorption process is fundamental to understand the nature of the elementary chemical processes of adsorbates, as the energetics of bonding, the specification of the chemical nature of the bound species and the nature and magnitude of interactional effect between adsorbed species. We focused our attention on the applications of Thermal Desorption Spectroscopy (TDS) to High-Energies Physics, Astrophysics and Geophysics; in fact this technique was used, respectively, to investigate the molecular hydrogen adsorption on carbon nanotubes, the effects of electron bombardment on ammonia and methane ices and changes of zoisite mineral after heating. The molecular hydrogen adsorption on carbon nanotubes was studied to find a possible solution to vacuum system problems of Large Hadron Collider (LHC); in fact, the circular path of photon beams produces synchrotron radiation which deteriorates LHC vacuum desorbing gas molecules from the ring walls. Among the desorbed species the most problematic to pump out is H2. Since LHC elements operate at low temperatures, a possible solution to vacuum problem is the installation of cryosorbent materials on the LHC walls. In this work we study the possibility to use carbon nanotubes as criosorbers in future accelerators. Our sample, furnished by Prof. Nagy group of Chemical Engineering Department of Calabria University, is constituted by MWNTs synthesized by chemical vapor deposition using C2H4 and subsequently purified. Our investigations confirm that the carbon nanotubes have a great adsorption capacity also at low temperatures both for H2 and noble gases as Kr; then we observed that H2 adsorption on CNT is described by a first kinetic-order, while Kr adsorption is characterized by a zero kinetic-order. By means of TDS we calculate the activation energy for H2 adsorption on carbon nanotubes and we found a value of about 3KJ/mol, perfectly coherent with theoretic one. Moreover, from a comparison between nanotubes and other carbon-based material (as charcoal), we noted that adsorption efficiency for CNT is almost an order of magnitude higher then charcoal. So carbon nanotubes are good candidates to cryosorbers in future accelerators. 2 As Thermal Desorption Spectroscopy application to Astrophysics we studied the effect of electron bombardment on ammonia and methane ices. The interstellar medium is composed for 99% by gas; molecules, atoms and radicals at gas state condense on dust grains surface of molecular clouds (at 10 K) creating an icy mantle with a thickness of 0.1 μm. The presence of ices is confirmed by IR spectroscopy of obscured stellar sources and in interstellar grains are localized solid mixture containing H2O, CO, CH4 and NH3. In these environments ices are subjected to chemical and physical processes, specifically to bombardment of photons and cosmic rays, with the consequent synthesis of new organic species In this work we conducted an investigation of the chemical processing of ammonia and methane ices subjected to energetic electrons. By Thermal Desorption Spectroscopy we verify the production of new organic species, after energetic irradiation in interstellar ices, as diazene (N2H2), ethane (C2H6) and acetylene (C2H2). Finally, in Geophysics and Petrology Thermal Desorption Spectroscopy can be used to study minerals chemical composition. Our interest was focused on zoisite and the sample investigated was furnished by prof. Ajò from “Institute of Inorganic Chemistry and Surfaces” of CNR, in Padova. In this work we used TDS to investigate zoisite behaviour during heating form room temperature to 650oC and to understand if its modification into tanzanite variety after heating is due to structural changes or to a dehydration mechanism.
Adsorption properties of carbon nanotubes and application of thermal desoprtion spectroscopy to ammonia and methane ices and zoisite
(2014-05-15) Vasta, Roberta; Bonanno, Assunta; Falcone, Giovanni
In this work we wanted to underline the importance of Thermal Desorption Spectroscopy and its applications to several branches of Physics. Temperature-programmed desorption techniques (TPD) are important to determinate kinetic and thermodynamic parameters of desorption processes and decomposition reactions. Knowledge of the nature of the desorption process is fundamental to understand the nature of the elementary chemical processes of adsorbates, as the energetics of bonding, the specification of the chemical nature of the bound species and the nature and magnitude of interactional effect between adsorbed species. We focused our attention on the applications of Thermal Desorption Spectroscopy (TDS) to High-Energies Physics, Astrophysics and Geophysics; in fact this technique was used, respectively, to investigate the molecular hydrogen adsorption on carbon nanotubes, the effects of electron bombardment on ammonia and methane ices and changes of zoisite mineral after heating. The molecular hydrogen adsorption on carbon nanotubes was studied to find a possible solution to vacuum system problems of Large Hadron Collider (LHC); in fact, the circular path of photon beams produces synchrotron radiation which deteriorates LHC vacuum desorbing gas molecules from the ring walls. Among the desorbed species the most problematic to pump out is H2. Since LHC elements operate at low temperatures, a possible solution to vacuum problem is the installation of cryosorbent materials on the LHC walls. In this work we study the possibility to use carbon nanotubes as criosorbers in future accelerators. Our sample, furnished by Prof. Nagy group of Chemical Engineering Department of Calabria University, is constituted by MWNTs synthesized by chemical vapor deposition using C2H4 and subsequently purified. Our investigations confirm that the carbon nanotubes have a great adsorption capacity also at low temperatures both for H2 and noble gases as Kr; then we observed that H2 adsorption on CNT is described by a first kinetic-order, while Kr adsorption is characterized by a zero kinetic-order. By means of TDS we calculate the activation energy for H2 adsorption on carbon nanotubes and we found a value of about 3KJ/mol, perfectly coherent with theoretic one. Moreover, from a comparison between nanotubes and other carbon-based material (as charcoal), we noted that adsorption efficiency for CNT is almost an order of magnitude higher then charcoal. So carbon nanotubes are good candidates to cryosorbers in future accelerators. 2 As Thermal Desorption Spectroscopy application to Astrophysics we studied the effect of electron bombardment on ammonia and methane ices. The interstellar medium is composed for 99% by gas; molecules, atoms and radicals at gas state condense on dust grains surface of molecular clouds (at 10 K) creating an icy mantle with a thickness of 0.1 μm. The presence of ices is confirmed by IR spectroscopy of obscured stellar sources and in interstellar grains are localized solid mixture containing H2O, CO, CH4 and NH3. In these environments ices are subjected to chemical and physical processes, specifically to bombardment of photons and cosmic rays, with the consequent synthesis of new organic species In this work we conducted an investigation of the chemical processing of ammonia and methane ices subjected to energetic electrons. By Thermal Desorption Spectroscopy we verify the production of new organic species, after energetic irradiation in interstellar ices, as diazene (N2H2), ethane (C2H6) and acetylene (C2H2). Finally, in Geophysics and Petrology Thermal Desorption Spectroscopy can be used to study minerals chemical composition. Our interest was focused on zoisite and the sample investigated was furnished by prof. Ajò from “Institute of Inorganic Chemistry and Surfaces” of CNR, in Padova. In this work we used TDS to investigate zoisite behaviour during heating form room temperature to 650oC and to understand if its modification into tanzanite variety after heating is due to structural changes or to a dehydration mechanism.
Advanced Materials (Ceramics in particular) for Structural Applications
(2015-12-15) Koduru, Hari Krishna; Bartolino, Roberto; Versace, Carlo; Scaramuzza, Nicola
The study of ‘Intrinsic and Metal nano particles doped polymer thin films for soft matter applications and nanostructured Hyperbolic metamaterials’ is an challenging and dynamic field of research with significant implications in the development of novel technologies, like gas sensors, bio-medical application and engineering of spontaneous emission of florescent molecules. In the present investigation, we presented research work in two directions. We prepared Polymer thin films by homemade Cold Plasma Polymerization technique and studied their Microstructural, Optical and dielectric responses as a function of thin film growth parameters, in view of gas sensor applications. In other direction, we fabricated lamellar structured Hyperbolic Metamaterials by employing physical and chemical vapour thin film deposition techniques and employed them as effective substrates to engineer the life time of florescent dye molecules. The first part of this thesis is devoted to preparing Polypyrrole (PPy) thin films of nano sized thickness, by Cold plasma polymerization technique and analyzing the influence of Plasma power on Microstructural, Optical, wetting and dielectric properties of grown PPy films. Fabricating layered structures of “PVA/AgNPs/PVA” thin films to investigate the influence of rate of distribution of AgNPs on dielectric responses of PVA matrix to employ them as a gas sensor applications, whose study is still open and is getting substantial interest in industrial and academic environments. Enhancement of spontaneous emission is a dynamic and challenging fundamental quantum phenomenon in optics and in nutshell it opens new avenues for spectrum of futuristic applications. Metamaterials are artificially designed nanocomposite materials, in which bulk electromagnetic properties arise due to underlying structural resonances and near field coupling between the designed sub-wavelength building blocks. Metamaterials promise to alleviate the classical limitations of optics and led to exotic applications such as negative refraction, sub-wavelength resolution imaging, invisibility devices and perfect absorbers. In the second part of this thesis, we fabricated Hyperbolic metamaterials and proposed new grating coupled hyperbolic metamaterial (GCHMM) configuration for the enhancement of spontaneous emission rate of dye molecules by exploiting the unique property of a hypergrating to outcouple and extract the non-radiative plasmonic modes.
Advanced numerical models for highly frustrated liquid crystalline phases
(2014-11-03) de Jesus, Caldera Teresita; Bartolino, Roberto; Versace, Carlo C.; Barberi, Riccardo; Lombardo, Giuseppe
Advanced plasmonic devices: enhancement of the properties of organic and perovskite solar cell through gold nanoparticles
(2019-07-23) Servidio, Alessandro; Carbone, Vincenzo; ermine, Roberto ,; Golemme, Attilio
Advances in biocatalytic membrane reactors development
(2017-07-21) Ranieri, Giuseppe; Carbone, Vincenzo; Giorno, Lidietta
Air quality and pollutant modelling in the mediterranean regionDocumenti elettronici
(2013-11-11) Gengarelli, Christian Natale; Bertolini, Roberto; Pirrone, Nicola; Carbone, Vincenzo; Hedgecock, Michael
L'inquinamento atmosferico viene de nito come la presenza di sostanze che possono avere e etti dannosi sulla salute umana o sull'intero sistema ambientale (EC, 2008), causando e etti misurabili sugli animali, sulla vegetazione e sui diversi materiali. Queste sostanze, dette inquinanti, usualmente non sono presenti nella normale composizione atmosferica o lo sono ma a concentrazioni estremamente basse. Tra i pi u pericolosi inquinanti presenti in atmosfera c' e il mercurio (Hg), un inquinante globale sotto controllo soprattutto negli ultimi anni (UNEP, 2013b; Mason et al., 2012; Driscoll et al., 2013) in quanto provoca gravi e etti nocivi sulla salute umana. Elevate concentrazioni di mercurio negli ecosistemi sono causate dalle emissioni dirette, ma anche da reazioni chimiche che avvengono in atmosfera e dalle condizioni meteorologiche che, governate dalla sica dell'atmosfera, regolano la distribuzione, il trasporto e la deposizione del mercurio. Per individuare le cause delle elevate concentrazioni di inquinanti in atmosfera e necessaria un adeguata rete di monitoraggio, ma e molto complicato coprire vaste aree geogra che con stazioni di misura. Diviene dunque necessario ricorrere a modelli matematici che simulano le condizioni atmosferiche dal punto di vista sia meteorologico che chimico, in modo da ottenere i fattori sui quali e possibile intervenire per migliorare la qualit a dell'aria. Questo lavoro di tesi mostra lo sviluppo di un modello regionale online che simula il ciclo atmosferico del mercurio, in modo da valutare ed identi care le relazioni tra sorgenti e recettori a scala regionale e gli andamenti temporali degli scenari di emissione di mercurio attuali e futuri. Il risultato e una versione ampliata del modello numerico per la chimica ed il trasporto atmosferico WRF/Chem (modello Weather Research and Forecasting per la meteorologia integrato con la chimica atmosferica, Grell et al. (2005)), che pu o simulare il ciclo atmosferico del mercurio online. Questa versione del modello e in grado di riprodurre i campi di concentrazione ed i ussi di deposizione del mercurio a scala regionale, includendo le emissioni da sorgenti sia antropogeniche che naturali e simulando le interazioni e le reazioni chimiche che avvengono in atmosfera, nonch e i processi di deposizione. Per lo sviluppo di questo modello e stato necessario indagare i diversi aspetti della chimica del mercurio, analizzando ed implementando le interazioni con gli altri gas presenti in atmosfera, con la radiazione solare, con il vapore acqueo e con la pioggia; queste interazioni regolano i processi di ossidazione, riduzione e deposizione del mercurio. Inoltre sono stati implementati nel modello i processi di emissione da parte di sorgenti antropiche e naturali, parametrizzando le emissioni di mercurio dovute agli incendi boschivi e l'evasione di mercurio nell'interfaccia atmosfera - super ce del mare. Oltre alle deposizioni di mercurio da parte delle piogge (deposizione wet) sono stati implementati i meccanismi per deposizione al suolo dovuta alla forza gravitazionale ed ai moti atmosferici (deposizione dry). Il modello e in grado di riprodurre la variazione stagionale delle concentrazioni di mercurio, rappresentando adeguatamente anche gli andamenti di HgII e HgP nello strato atmosferico al limite con la super ce del Mar Mediterraneo (Mediterranean MBL). La medie annuali delle deposizioni di mercurio wet e dry modellate sono simili, ma con di erente distribuzione spaziale: la deposizione wet domina nelle zone umide mentre la deposizione dry e maggiore vicino alle sorgenti di emissione. Comparando le deposizioni con l'evasione di mercurio dalla super ce del mare risulta che il Mar Mediterraneo e una sorgente di mercurio per tutta l'area, con circa 70Mg di mercurio emessi in un anno. I risultati suggeriscono inoltre che nel MBL Mediterraneo il Bromo e un importante ossidante del mercurio. Il modello WRF/Chem e stato inizialmente usato per investigare la produzione fotochimica di un importante costituente atmosferico che in uenza il ciclo del mercurio nell'area del Mar Mediterraneo, l'ozono troposferico (O3). Oltre ad in uenzare il ciclo del mercurio, l'ozono e anche un pericoloso inquinante: elevate concentrazioni di ozono in prossimit a del suolo sono infatti dannose sia per la salute umana che per la produzione agricola. L'analisi modellistica dell'inquinamento da ozono troposferico mostra una forte in- uenza delle emissioni prodotte dalle navi che transitano nel Mar Mediterraneo, stimando il loro contributo in circa il 10{20% delle concentrazioni di ozono nelle aree continentali.
Applicazione dei big data nel turismo, marketing ed education
(Università della Calabria, 2020-03-18) Giglio, Simona; Critelli, Salvatore; Pantano, Pietro
Il mondo è attualmente inondato da dati e l’avanzare delle tecnologie digitali amplifica questo fenomeno in modo esponenziale. Tale fenomeno viene etichettato con il concetto di Big Data ovvero le tracce digitali che le nostre attività quotidiane lasciano per effetto dell’uso massiccio dei sistemi ICT (Information Communication Technologies). I Big Data sono diventati il nuovo microscopio che rende “misurabile” la società. Per tali ragioni, la ricerca è incentrata sull’analisi dei Big data, estratti dai social media, da indagini online, da piattaforme di recensioni e da database, attraverso l’applicazione di tecniche e strumenti sviluppati nell’ambito dell’Intelligenza Artificiale. Algoritmi di machine learning, analisi semantica ed analisi statistica sono stati utilizzati per estrarre, dai Big Data, informazione sotto forma di “conoscenza” e “valore”, dimostrando come dati di grandi dimensioni possano fungere da ricca fonte di informazione, da un lato, per comprendere il comportamento dell’utente, parte integrante di una società complessa (conoscenza), e dall’altro, per sostenere i processi decisionali e i servizi forniti agli utenti/consumatori (valore). Il lavoro si caratterizza per un approccio multidisciplinare tra settori differenti quali le scienze sociali, le scienze statistiche e l’informatica. Questo ha permesso di fondare la ricerca sui Big Data nella teoria, e fornire un efficace recupero e analisi dei dati nella pratica. Le tecniche di machine learning sono state applicate per (i) il riconoscimento delle immagini, (ii) per la creazione di cluster, (iii) per l’analisi del testo (sentiment analysis) e (iv) per la profilazione di classi di utenti. Per il riconoscimento delle immagini l’approccio ha richiamato le reti neurali artificiali (deep artificial neural networks), algoritmi e sistemi computazionali ispirati al cervello umano utilizzando le potenzialità del programma Wolfram Mathematica e la disponibilità di dati estratti da social network quali Flickr, Twitter, Instagram ed altre piattaforme come TripAdvisor. Gli strumenti utilizzati nella ricerca hanno permesso di indagare e di rilevare in modo oggettivo dall’analisi di immagini e di testi condivisi sul web, alcuni comportamenti cognitivi degli utenti/consumatori alla base delle loro scelte nonché l’attrattività di una destinazione turistica e la qualità dell’esperienza dell’utente. Lo studio del significato delle parole nel testo ha aperto la strada al web semantico che permette ad un utente di acquisire informazioni approfondite durante una ricerca attraverso un sistema formato da una rete di relazioni e connessioni tra documenti. Partendo dalle ricerche di Ogden e Richards sullo studio del significato e di Jakobson che studiò i processi comunicativi, si è cercato di strutturare e sistematizzare un processo che riflette un atto comunicativo ed informativo tale che un simbolo (immagine) attraverso l’applicazione di un significante (machine learning che si sostituisce al processo mentale proprio dell’uomo) permettesse l’esplicitazione di un referente (oggetto\etichetta) che opportunatamente porta alla trasmissione di un messaggio sotto forma di conoscenza. Il tutto coordinato da un sistema in grado di coniugare fattori differenti in un’ottica interdisciplinare dove l’analisi dei dati combacia perfettamente con la linguistica. Attingendo da studi precedenti, i risultati raggiunti dimostrano che gli algoritmi di analisi dei Big Data quali l’apprendimento automatico contribuiscono da un lato alla comprensione sull’esperienza dell’utente verso un luogo, una destinazione; d’altra parte, la loro analisi fornisce una conoscenza sistematica delle valutazioni dei consumatori su un determinato prodotto o servizio e verso lo sviluppo di una sorta di “intelligenza sociale”. Inoltre i risultati della ricerca propongono come, un approccio più sofisticato al monitoraggio dei social media nel contesto turistico e nel marketing, nonché nel settore dell’education, possa contribuire a migliorare le decisioni strategiche e le politiche operative degli stakeholder nonché ad avere una visione psicologica sugli atteggiamenti e sul comportamento di un ampio spettro di utenti.
Applicazione di tecniche di datazione ed indagini diagnostiche su reperti archeologici ossei, ceramici e lapidei
(2013-11-28) Renzelli, Diana; Pantano, Pietro S.; Oliva, Antonino
Archaeometric studies bymeans of complementary and non-destructive physical methodologies with micrometric resolution
(Università della Calabria, 2021-07-19) Smeriglio, Andrea; Cipparrone, Gabriella; Formoso, Vincenzo; Jacobsen, Kindberg
The approach to the study of cultural heritage and archaeology find is highly interdisciplinary. The archaeometry expert has to be a multidisciplinary figure with different skills in hard sciences (physical, chemical, biological, earth sciences and engineering), humanities (art historians, philologists, curators) and technical disciplines (restorers and conservators). Today the archaeometry expert needs a palette of non-destructive and non-invasive techniques, to improve the understanding of the manufacture, the evolution and/or degradation during the time of the archaeological find. The aims of this thesis is to display the result of archaeometric studies performed in my PhD research, and describe the non-destructive physical methodology and the approaches used to address archaeological questions and problems. The X-ray μCT experimental apparatus implemented at the STAR-Lab facility realized under the PON MaTeRia project, at the University of Calabria (Italy), give us a possibility to acquire several images useful to inspecting the internal morphology of an object. It is a non-destructive diagnostic method used to characterize material microstructure in three dimensions with resolution of the order of micrometer. Artax 400 is a portable μXRF developed by Bruker for archaeometric studies. μXRF is an analytical technique for elemental characterization that provides both qualitative and quantitative information. It’s a non-destructive method which does not require a specific sample preparation, and it allows to carry out investigations in situ. These complementary and non-destructive physical methodologies were used and implemented for the investigation of different archaeological finds from different archaeological contexts. In particular, five case studies are described below: 1. The aim of this case study is to determine the materials, the production process and the technological features of three silver plated coins (two Roman denarii and one Greek statere) preserved in the “Brettii and Enotri” museum in Cosenza. 2. The aim of this case study is to understand the oxidation processes, to know the constituent material and to find hidden signs or inscriptions of two completely oxidated coins preserved in the “Brettii and Enotri” museum in Cosenza. 3. The aim of the current case study is to determine the materials and technological features of a unicum object and to read possible inscriptions and decorations under the superficial encrustations of a bronze plaque. Both archaeological finds have been excavated in the archaeological site of Timpone della Motta, in Francavilla Marittima (CS). 4. In this case study the chemical composition of the bronze alloy and physical technical characteristics of two bronze anthropomorphic couples as pendants (dating to the Early Iron Age) have been studied. The first, called “type B”, were discovered in the archaeological site of Pietrapaola (CS), however the second, called “type A”, . were discovered in archaeological site of Bucita-Rossano (CS). 5. The aim of this case study is to investigate the conservation status and the chemical composition of 12 Magno-Greek bronze mirrors. These prestige goods are a clear example of the high level reached by the handicraft of Magna Graecia. They are preserved in the National Archaeological Museum of Locri Epizephyrii. They were discovered in the grave of the Contrada Lucifero Necropolis and they are dated between the second half of the VI century b.C. and the first half of the IV century b.C.
Aspects of Integrability in AdS/CFT duality
(2011) Infusino, Gabriele; Rossi, Marco; Falcone, Giovanni
Aspects of phase transitions in gauge theories and spin models on the lattice
(2016-02-26) Cuteri, Francesca; Papa, Alessandro; Fiore, Roberto
The main focus of this thesis are phase transitions both in gauge theories, in particular in Quantum ChromoDynamics (QCD), and in two-dimensional spin models. The approach is numeric, relying on dedicated simulation and analysis softwares, and takes advantage of the possibility to discretize our theories, and describe our models, on a lattice. Three di erent kind of investigations have been carried out, two of them concerning QCD. The thermal decon nement/chiral phase transition in QCD at zero chemical potential has been indeed, indirectly studied, respectively via the characterization of color- eld ux tubes, as footprints for con nement in SU(3) pure gauge theory, and via a study at imaginary chemical potential for the case of full QCD with two degenerate avors of dynamical quarks Nf = 2. In the former case a systematic study of the longitudinal pro le of the chromoelectric eld produced by the strong interaction of a pair of quark and antiquark in the QCD vacuum has been realized, both at zero and nonzero temperature. Measurements have been performed in numerical simulations implementing the appropriate eld-related lattice operator. The characteristic sizes of the ux tubes have been extracted through a tting procedure based on a well known picture for the con nement phenomenon called \dual superconductor model" that traces an analogy between color con nement and superconductivity. Such a picture is found to successfully describe our numerical results for the chromoelectric eld distribution at zero temperature. Taking one step further in the dual analogy, the pro le of the ux tube has been then studied at nite temperature and across the decon nement transition. However, results indicate that the analogy cannot be pushed so far: as the temperature is increased towards and above the decon nement temperature Tc, the amplitude of the eld inside the ux tube gets considerably smaller, while the shape of the ux tube does not vary appreciably at the onset of decon nement. An "evaporation" of ux tubes is observed that has no counterpart in ordinary (type-II) superconductivity and let the tube structure survive the phase transition, consistently with observations in heavy-ion collision experiments. A somewhat di erent analysis about the thermal phase transition in Nf = 2 QCD (where direct studies are prevented either by the well known sign problem or by high numerical costs) can be carried out at imaginary values of chemical potential that are critical for the Roberge-Weiss (RW) phase transition. In particular, the nature of the RW phase transition at the endpoint of the rst order critical RW line has been investigated. It is found to depend on the quark masses in a way that it is a triple rst-order point in the limit of zero (in nite) masses and a second order critical endpoint at intermediate masses. Similar results are relevant for the understanding of the nature of the thermal transition at = 0. Coming to spin models and, to be more speci c, to two-dimensional spin models characterized by non-Abelian symmetry groups U(2) and SU(N) for N = 5; 8, the existence of in nite order (BKT) phase transition has been checked. Such transitions were expected on the basis of analytical computations and have been, indeed, numerically detected in all considered models. By means of nite size scaling analysis it has been also observed that the BKT phase transition that takes place in U(2) models belongs to the universality class of the two-dimensional XY model.
Astroparticle physics as a telescope for solar interior, galactic and extragalactic structures
(2013-11-25) D'Alessi, Loris; Bartolino, Roberto; Carbone, Vincenzo
Astroparticle physics provide a fundamental tool to investigate the astrophysical structures at different scales. In this thesis the results are presented of three years of research focused on time variations on solar neutrino flux, galactic cosmic rays and fine-structure constant as observed from quasar spectra. These topics are nowadays crucial to investigate structures which otherwise result difficult to probe. In particular time variations in solar neutrinos can give a real time description of the dynamics which take place in the inner regions of the Sun, while the study of galactic cosmic rays through the observation of muons produced by the interaction of the formers with the atmosphere, may give us precious informations on the interaction between TeV particles and heliospheric magnetic fields. Finally the recent observations of variations in the fine-structure constant value from the analysis of quasar absorption spectra, offer new possibilities to probe physical laws at cosmological scales. The thesis is structured as follows. In Chapter One are discussed quasi-biennial oscillations observed on solar neutrino flux and a phenomenological model is proposed to interpret the observed time variations. In the scenario described by the model, the interaction between solar neutrinos and solar matter mediated by magnetogravity modes, is modulated by a background magnetic field varying in time on quasi-biennial time scales. In Chapter Two the 11-yr component recently observed in cosmic muon data from Gran Sasso experiments of MACRO, LVD and Borexino has been reconstructed through the EMD analysis technique. In Chapter Three the data of fine-structure constant variations as observed in the quasar absorption spectra have been analyzed to search for temporal coherent structures. The thesis is completed by the description in appendix of a new algorithm based on Monte Carlo methods to assign a confidence interval to the IMFs extracted with the EMD analysis, and the application of this method to study the proton and neutrino distributions used in the OPERA experiment for the neutrino velocity measurement. Another appendix is dedicated to detailed description of the effects induced on the magnetogravity spectrum by a background magnetic field with a low-pass bandwidth, thus generalizing the theory of magneto-gravity modes in presence of a time-dependent background magnetic field.